CVE-2021-33766
Microsoft Exchange Server Information Disclosure Vulnerability
- Published
- Jul 14, 2021
- Updated
- Aug 10, 2026
- Assigning CNA
- microsoft
- Evidence observed
- Jan 18, 2022
Primary CVSS
nvd · CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NHigh · next 30 days
- Percentile
- 99.9%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
CISA Known Exploited
This CVE appears in the CISA Known Exploited Vulnerabilities catalog.
Summary
Microsoft Exchange Server Information Disclosure Vulnerability
Sources
2ProxyToken (CVE-2021-33766) : An Authentication Bypass in Microsoft Exchange Server POC exploit
- CVE-2021-33766-ProxyTokenExploit
Proof-of-concept exploit for CVE-2021-33766 (ProxyToken) authentication bypass in Microsoft Exchange Server. Supports single and batch target detection and mail forwarding rule modification.
Responsible use
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